β-globin gene cluster haplotypes in iranian patients with β-thalassemia

introduction: β-globin gene cluster haplotypes are useful in diagnosis of particular molecular defects in β-thalassemia, prenatal diagnosis of β-thalassemia, and elucidating population affinities. methods: β-globin gene cluster haplotypes were studied in 150 β-thalassemia minor and 52 healthy in-dividuals from the fars province of iran. dna was extracted from leukocytes of whole blood by phe-nol-chloroform. haplotype was determined by pcr-rflp technique. } results: there were 26 out of 150 with homozygous haplotypes. haplotype i was found as the most prevalent haplotype among both patients and normal individuals. out of 26 patients bearing homozy-gous haplotypes, 12 (46.2%) had typical haplotype i and 3 (11.5%) had atypical haplotype i. the prevalence of haplotype i in normal control subjects was around 43% (45 out of 104 βa chromo-somes). the second prevalent haplotype was haplotypes v (15.4%) and iii (15.4%) for homozygous patients and controls, respectively. the most frequent mutation in patients was ivs ii.1 (g→a) that was not linked to a single haplotype. ivs i.110 (g→a) mutation was linked to haplotype i. mutation in codon 30 (g→a) was associated with haplotype v. conclusion: being haplotype i the most prevalent haplotype in β-thal and βa chromosomes, implies that β-thalassemia mutations might have arisen in the chromosomal background common in the popula-tion, rather than due to selection pressure or gene flow (migration). patients with haplotype ix had the highest hbf levels compared to other haplotypes.